Drucella Andersen
Headquarters, Washington, D.C.
March 4, l992
(Phone: 202/453-8613)
Don Haley
Ames-Dryden Flight Research Facility, Edwards, Calif.
(Phone: 805/258-3456)
RELEASE: 92-29
NASP PROPULSION TESTS PLANNED FOR NASA SR-71
A key propulsion concept for the X-30 National Aero-Space
Plane (NASP) is being designed for tests on a NASA SR-71A
"Blackbird" research aircraft. The experiment is expected to
be the first major research project flown in the SR-71
program in NASA service.
An SR-71A, which can cruise at three times the speed of
sound, would act as a high-speed testbed to prove the concept
of burning hydrogen fuel outside the X-30's engine exhaust
nozzles as a way to improve overall flight efficiency. If
the initial design work is accepted and SR-71 program
operations are approved through the 1993 fiscal year, the
SR-71A will be modified and flown at NASA's Ames-Dryden
Flight Research Facility, Edwards, Calif.
The X-30 is a future flight research vehicle that will
take off horizontally, fly into Earth orbit and return
through Earth's atmosphere for a runway landing. The NASP
Joint Program Office, Wright-Patterson AFB, Ohio, is funding
preliminary design work for the experiment. The NASP program
is a joint effort involving NASA, the Department of Defense
and a U.S. industry team.
The bottom rear part of the X-30's fuselage will be shaped
to act as an exhaust nozzle, which will increase thrust. But
computer and wind tunnel studies predict that the area near
the exhaust will experience low pressures when the Aero-Space
Plane flies at lower altitudes and at speeds from Mach 0.8 to
Mach 3.
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The low pressures will increase drag and reduce the
vehicle's maximum planned performance. Injecting hydrogen
fuel into the air stream under the X-30's engines and then
igniting it -- a concept dubbed "external burning" -- is
being studied as a way to increase pressure near the engine
nozzles to reduce drag.
"The NASP external burning concept has progressed steadily
from the drawing board through wind tunnel tests and computer
simulations to the point where we're ready to move to larger
scale, high-speed flight tests" said Vincent Rausch, Director
for the National Aero-Space Plane at NASA Headquarters,
Washington, D.C. "The tests with NASA's SR-71A should be an
important milestone in that effort."
The external burning experiment will mount a 10-foot-long,
half-scale X-30-type aft-engine cowling and exhaust nozzle
model atop the SR-71A's fuselage midway between the nose and
twin vertical rudders. According to David Lux, SR-71 Project
Manager at Ames-Dryden, the test fixture's location on the
aircraft will be free from aerodynamic disturbances.
"We'll be flight testing the experiment to a speed up to
Mach 3," said Lux. "We believe this type of flight
environment will give us a true simulation of what external
burning will be on the X-30."
Current plans call for about 10 flights of the external
burning experiment at speeds up to Mach 1.5. The final six
flights will be made at speeds up to Mach 3. The tests will
study ignition limits of the hydrogen at high speeds,
conditions that could lead to engine flameout and levels of
turbulence that may result from the burning process.
The hydrogen will be carried in seven pressurized tanks
located in chine equipment bays that run along the sides of
the SR-71's fuselage. The fuel will be fed to 19 openings on
the test model and dispersed into the exhaust flow. Sensors
in the exhaust plume area will record air pressure and
temperature data for comparison with earlier computer and
wind tunnel results.
The test aircraft for the external burning experiment is
one of three SR-71s on loan to NASA from the U.S. Air Force
for use as high-speed research testbeds. According to John
Lutes, SR-71 Program Manager at NASA Headquarters, a
Dryden-led inter-center team is developing a national plan
involving industry, universities and other government
agencies. "The purpose of the planning effort is to identify
experiment needs that would use the unique flight research
capabilities offered by these aircraft," said Lutes.
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Tests with a small "boilerplate" fixture previously proved
that hydrogen can be burned externally at supersonic speeds.
The 14-inch-long test apparatus was mounted on the wing tip
of an F-18 and flown to Mach 1.26 at the Naval Air Test
Center, Patuxent River, Md.
The external burning project participants are Ames-Dryden;
NASA's Lewis Research Center, Cleveland; the Naval Air Test
Center; Lockheed Advanced Development Company, Burbank,
Calif.; The Johns Hopkins University Applied Physics Lab,
Laurel, Md.; and the Air Force Flight Test Center, Edwards
AFB, Calif.
-end-
NOTE TO EDITORS: Photographs are available to illustrate
this release by
calling 202/453-8375.
Color: 92-HC-110 B&W: 92-H-127
92-HC-111 92-H-128